Drones monitor and measure landfills, pipelines, and solar farms.
The California Air Resources Board (CARB) is amending its Landfill Methane Regulation (LMR) to strengthen landfill compliance and meet the state’s target of reducing methane emissions by 40% by 2030. The rules target steep emissions reductions through enhanced surface monitoring, including drone-mounted scanners, robotic sensors, and remote monitoring, as well as stricter wellhead thresholds, among other measures.
The CARB-proposed amendments will have significant impacts on landfill and gas collection and control systems (GCCS), for which owners and operators will need to plan and implement to meet the requirements. As the nation’s top engineering specialist firm in this sector (ENR Solid Waste and Environmental Sourcebook), SCS Engineers has prepared articles and videos to assist landfill owners/operators in complying with these new requirements, including proactive measures that can be deployed to minimize impacts, planning for additional staffing support to complete all of the new monitoring, new or modified GCCS equipment and other infrastructure that will be needed, and new technology necessary to meet new deadlines.
As essential services, or any business for that matter, the changes require additional budget and capital investment to meet extensive surface and leak-monitoring and repair protocols, tighter regulatory timelines for installing GCCS, and more frequent and extensive monitoring and analysis of cover integrity, temperature, oxygen, and liquid levels.
Planning begins now.
SCS’s first article summarizes the key changes and highlights the most salient points of the revised LMR. The companion educational video and slide set are available free of charge to the public and can serve as a starting point for owners, operators, compliance staff, field technicians, and engineers in landfill and gas management, including energy recovery and renewable natural gas facilities.
CARB Landfill Methane Regulations Free Resources:
Paper detailing the technical changes and summarizing salient steps.
Educational video provides a detailed overview of CARB’s landfill methane rule amendments, with actionable recommendations for landfill operators and compliance teams to assess site status, plan for new requirements, and budget for anticipated operational and capital changes.
As demand for securing domestic sources of critical minerals grows, mapping and quantifying their geologic sources is more important than ever. These critical minerals often escaped notice during historical exploration because attention was focused on commodity metals (e.g., gold, silver, copper), and their concentrations are often significantly lower than those of the precious metals. Exploratory drilling can help significantly close the gap in critical mineral data scarcity across the nation, reducing risk from both technoeconomic and environmental standpoints.
Let’s look at a project in Missouri. The Missouri Geological Survey has expanded its efforts to better understand the subsurface geology as it evaluates formations that may contain rare-earth elements and other strategic resources. These broader state efforts reflect a growing nationwide focus on geologic mapping, core preservation, and resource evaluation to find and quantify critical minerals in the U.S.
Our SCS Critical Minerals team, along with HAD, Inc. drillers, recently supported one of these efforts through deep bedrock coring designed to collect high-quality, continuous core for geologic characterization, resource assessment, and long-term archival use. The work included coordinating safe drilling operations, overseeing continuous core recovery, and supporting lithologic logging and field documentation.
The SCS team helps extract reliable subsurface data from deep bedrock intervals, including dolomitic units and underlying Precambrian formations, strengthening our understanding of mineralization potential and the geology of the Viburnum Trend. Data from this drill core will help to identify what critical minerals may be present, how they occur, and in what concentrations– all of which are essential to evaluate their potential for recovery and utilization.
The Missouri Geological Survey will analyze each core for critical mineral and rare-earth element concentrations using a suite of analytical tools, including x-ray fluorescence (XRF) scanning and other geochemical characterization methods. These data will help researchers better understand what elements are present, how concentrations vary with depth and geology, and how mineralization occurs within the subsurface.
Projects like this highlight the value of integrating drilling, coordination, geologic interpretation, and resource-focused evaluation into a single, well-executed field program that can be recreated across the U.S. As public and private stakeholders invest in domestic critical minerals and energy transition initiatives, we support efforts to turn subsurface data into actionable information to determine resource value and profitable extraction techniques while meeting rigorous mining regulations for environmental protection.
Mining is one of the most highly regulated and environmentally sensitive industries in the U.S. At the same time, federal and state priorities emphasize the strategic importance of domestic rare earth element and critical mineral production, both from conventional and, increasingly, unconventional resources. Learn more here, or contact one of our National Experts!
Environmental compliance in printing operations involves complex interactions between materials, production processes, and regulatory permits. Small operational changes, such as material substitutions, can significantly affect emissions calculations and compliance status, even if they seem minor.
Material changes affect compliance: Switching to materials with different VOC or hazardous air pollutant contents can increase a facility’s potential-to-emit (PTE), requiring updates to emissions calculations and permit conditions. These impacts often go unnoticed on the production floor but can create compliance risks later during inspections or reporting.
Emissions driven by mass balance: Printing air programs calculate emissions based on material usage multiplied by VOC/HAP content, adjusted for capture and control efficiencies. This approach offers operational flexibility but also introduces complexity, as small formulation changes directly affect emissions.
Material substitutions are common and risky: Frequent substitutions under supply chain pressure can alter VOC content, HAP speciation, vapor pressure, and control device assumptions, impacting emissions and permit compliance if not evaluated in advance.
Potential-to-Emit (PTE) is critical: Regulators focus on PTE, which considers maximum emissions under full operation. Changes in VOC content or production capacity can increase PTE, potentially breaching permit thresholds, especially for facilities operating under synthetic minor limits.
Operational drift from permit assumptions: Over time, facilities may shift materials, usage rates, or production levels without updating permits, leading to unintentional non-compliance despite ongoing emissions tracking.
Recordkeeping is foundational: Maintaining accurate VOC/HAP usage records, emissions calculations, control device data, and hazardous waste documentation is essential to demonstrate compliance during inspections and avoid issues arising from misaligned documentation.
Best practices for compliance management: Effective facilities integrate environmental reviews into change management, align operational and emissions data, keep permit limits visible to operations, establish material approval processes, involve environmental expertise early, and periodically recalibrate permit assumptions to prevent compliance gaps.
Salt Lake City’s rapid growth is expanding into areas affected by historic mining, where mine tailings—residual materials from ore processing—pose environmental and financial challenges. However, these tailings do not inherently preclude development; rather, they should be treated as specialized brownfields that can be safely redeveloped through informed due diligence and risk-based planning.
Understanding Mine Tailings in Salt Lake City’s Growth
Utah’s long mining history has left tailings spread across large areas, which were historically viewed as inert fill but now lie beneath or near expanding development corridors. These tailings are a common due diligence concern in real estate transactions, yet misconceptions about their impact can lead developers to overestimate remediation needs. Many tailings-affected sites can be redeveloped successfully using established environmental and engineering methods.
Mine Tailings as a Unique Brownfields Remediation Condition
Mine tailings qualify as brownfields—previously disturbed lands with environmental concerns—but differ from typical urban brownfields. Unlike discrete contamination sources, tailings are shallow, widespread, and usually contain elevated levels of metals such as arsenic, lead, cadmium, or mercury, spread uniformly across large areas. This lateral, shallow nature supports practical, risk-based solutions that focus on exposure management rather than full removal, protecting human health while controlling costs.
Regional Redevelopment Examples
Across the Salt Lake Valley, various redevelopment projects illustrate that mining legacies do not preclude development. Large master-planned communities, urban infill projects, former rail and industrial corridors, and river-adjacent developments have all successfully addressed historic environmental constraints by combining thorough planning, engineered controls, soil characterization, and exposure pathway evaluation. These examples demonstrate that early investigation and regulatory coordination enable routine and feasible brownfields redevelopment, including sites with mine tailings.
Due Diligence and Site Assessment
Effective redevelopment begins with comprehensive due diligence. Phase I Environmental Site Assessments identify historical mining or smelting activities through historical maps and records. If environmental concerns are found, Phase II investigations focus on soil metals characterization, the extent of impacted materials, and exposure pathways relevant to the proposed land use. These assessments inform feasibility assessments, cost estimation, site design, and purchase negotiations, reducing uncertainty and avoiding surprises later.
Utah’s Risk-Based Regulatory Framework
Utah employs a risk-based regulatory approach allowing tailored cleanup strategies based on site conditions and intended land use. Residential projects face stricter exposure standards than commercial or industrial uses. Common regulatory measures include engineered barriers (e.g., clean soil caps, pavement), construction soil management plans, and institutional controls that document site conditions and obligations. Voluntary cleanup programs offer regulatory certainty and liability protection, integrating environmental measures into project design rather than treating them as separate remedies.
Integrating Environmental Planning into Brownfields Remediation
Successful projects integrate environmental planning with civil engineering, grading, and construction sequencing. Tailings can be managed beneath building footprints, roads, or landscaped areas, acting as engineered caps. Excavated materials can sometimes be reused on-site under controlled conditions to reduce costs and traffic. Construction-phase soil management plans help contractors efficiently handle impacted soils, minimizing delays. This approach makes environmental considerations a manageable design parameter.
Managing Risk and Financial Considerations
Uncertainty is a major risk in brownfields redevelopment. Early characterization of tailings reduces uncertainty, enabling accurate cost modeling and contingency allocation. Additional risk-management tools include environmental insurance, negotiated purchase terms that reflect known conditions, and phased development strategies that spread cleanup costs over time. Sellers often price brownfields below market value due to perceived complexity, thereby giving knowledgeable developers a competitive advantage.
Importance for Salt Lake City’s Future Growth
Mine tailings are a distinctive redevelopment challenge in the Western U.S., with Salt Lake City central to this issue. As growth continues, the number of mining-impacted sites could increase. The key is not whether development can occur, but how thoughtfully and efficiently these sites are approached. Viewing mine tailings as brownfield opportunities rather than obstacles helps us unlock strategically located land while protecting health and the environment.
Conclusion: Key Takeaway
Mine tailings should not lead to project abandonment; instead, they should prompt early, informed inquiry, engagement of experienced professionals, and integration of environmental planning into development. Through due diligence and risk-based cleanup, tailings-impacted sites can support safe, vibrant, and profitable redevelopment that meets Salt Lake City’s growth goals and those of other states with similar conditions, such as Texas, New Mexico, and Nevada.
About the Author: Thomas (Tom) Gordon, EP, serves as a senior project manager with SCS Engineers in Salt Lake City and can be reached at SCS Engineers. He specializes in environmental due diligence, brownfields redevelopment, and risk-based cleanup strategies that support development projects across the region.
Additional Brownfields Remediation Resources:
How Will Radon Testing Impact My Development Project? Nationwide, enhanced standards, which took effect for loan applications after June 30, 2023, aim to improve air quality, with some 2025 updates beginning to refine these requirements. Recently, significant tightening of …
Brownfields and Voluntary Remediation Brownfields and voluntary remediation projects protect human health and the environment while restoring properties to beneficial use. SCS Engineers is a pioneer in supporting public-private partnerships for this type of redevelopment …
A recent examination by SCS Engineers Project Directors Evan Guignon, PE, and Michael Bradford, PE, into geosynthetic liner damage and repairs examined the permeability of geosynthetic liners used in waste containment systems. Their blog focuses on the significance of lined containment, the perception versus reality of liner permeability, liner installations, and liner repairs.
Importance of Lined Containment
Lined containment is crucial for managing solids, liquids, and gases in waste containment systems. Over the past 50 years, regulations such as CCR Title 27, Title 40 CFR, and RCRA (Subtitle D) have emphasized the need for effective containment.
Liner Permeability: Perception vs. Reality
The common perception is that geomembrane barriers are impermeable and that lined ponds are watertight. However, even a “perfect” liner will leak through diffusion. The leakage rate is influenced by the head over the liner, ranging from 1 to 8 gallons per acre per day for a standing head of 1 to 10 feet deep.
Minimizing Leaks: Liner Installations
Successful liner installations involve multiple stakeholders, including manufacturers, installers, design engineers, Construction Quality Assurance (CQA) engineers, and laboratories. Common defects and damages during installation include manufacturing defects (e.g., needle holes), installation errors, equipment damage, and issues with waste/material placement. CQA (Construction Quality Assurance) engineers play a vital role in minimizing these defects and ensuring the liner’s integrity.
Detecting and Managing Leaks
Single-lined facilities use groundwater or soil gas vapor monitoring wells to detect leaks. Dual-contained facilities use leak detection systems called pan lysimeters. The EPA Action Leakage Rate (ALR) recommends 1,000 gallons per acre per day for ponds and 100 gallons per acre per day for landfills. States can set their own ALR values based on the type and function of containment. If leaks exceed the ALR, inspections and repairs are performed to address liner containment.
Liner Repairs
When damage occurs to ponds or cells, repairs are necessary. Damage can be internal (e.g., wrinkles, creases) or external (e.g., rocks, operations, environmental factors). Long-term UV exposure, catastrophic events (e.g., fire or wildlife), and slope stability failures can also cause damage. Repair solutions for ponds and impoundments involve draining, cleaning, and replacing or repairing the liner. The process for cells includes exposing them, cleaning them, and repairing or replacing the liner.
Geosynthetic Liner Conclusion
The design, material manufacturing, installation, CQA services, lab testing, and leak/damage monitoring all contribute to the overall effectiveness of the containment system. CQA, with continuous monitoring and timely repairs, is essential to maintaining the integrity of these systems.
About the Authors:
Evan Guignon, PE has experience with semiannual reporting, exceedance tracking, and regulatory compliance related to environmental projects. He has training in AutoCAD Civil 3D Advanced Landfill Grading Applications and Plant 3D Modeling. Evan’s background includes stream restoration design planning and research involving cement sample preparation and testing according to ASTM standards. Mr. Guignon holds multiple state Professional Engineer licenses.
Michael Bradford, PE brings over 20 years of experience in civil engineering and project management, specializing in solid waste landfill and public works projects. His expertise includes landfill site planning, excavation and grading design, stormwater management, geosynthetic liner design, landfill gas collection and control systems, and leachate recovery system design. Mr. Bradford has managed large-scale landfill expansions and closure projects, including permitting and construction quality assurance, and holds multiple state Professional Engineer licenses as well as CQA/CQC certification for geosynthetic materials inspection. His work includes managing permit modifications and landfill expansions that extended facility life by decades, demonstrating his capability in regulatory compliance and technical leadership.
Evolving Geosynthetic Clay Liners and Coal Ash, Waste360, Eric Nelson of SCS and EREF Researcher Kuo Tian discuss polymer-modified Geosynthetic clay liners that can manage aggressive leachate and meet EPA’s requirements. The polymer-modified alternative system is a sustainable …
Practical Implications for Industrial and Solid Waste Facilities and the Real Estate Industry
Following the EPA’s announcements on PFAS/PFOS destruction and disposal since 2023 and the most recent Interim Guidance in April 2026, trends indicate widespread implications for industrial facilities, the real estate industry, and the solid waste and wastewater industries. PFAS controls and liability frameworks under CERCLA/Superfund and RCRA are tightening rather than rolling back, increasing compliance planning, monitoring, and litigation risk.
EPA finalized CERCLA hazardous substance designations for PFOA and PFOS (including salts and structural isomers) in April 2024; the rule took effect in July 2024 and is being defended by EPA amid ongoing D.C. Circuit litigation.
EPA is evaluating whether to designate seven additional PFAS as CERCLA hazardous substances (PFBS, PFHxS, PFNA, HFPO–DA/GenX, PFBA, PFHxA, and PFDA), following an April 2023 ANPRM.
For facilities and real estate transactions, the PFOA/PFOS CERCLA designations can affect Phase I ESA expectations, PRP determinations, closed-site reopeners, and release reporting; releases of ≥1 pound in 24 hours trigger CERCLA/EPCRA reporting obligations.
EPA proposed listing nine PFAS as RCRA hazardous constituents in February 2024 and intends to finalize the rule in 2026, which could expand corrective action obligations for generators and TSDFs with relevant solid waste management units.
In April 2026, EPA updated its interim guidance on PFAS/PFOS destruction and disposal (Version 2, April 2024), identifying options with lower potential for environmental release, such as permitted Subtitle C hazardous waste landfills, permitted hazardous waste combustors, and permitted Class I injection wells. SCS Engineers has prepared an SCS Technical Bulletin to walk our clients through the announcements and discuss the impact and trends.
The U.S. Environmental Protection Agency (USEPA) has issued guidance to simplify the Title V operating permit renewal process, emphasizing administrative efficiency while maintaining full compliance obligations. The guidance encourages focusing on changes rather than resubmitting unchanged information, but facilities must remain vigilant as renewals can reveal unresolved compliance issues.
Streamlined renewal process: The guidance permits the use of previously submitted materials, incorporation by reference, and directs agencies to concentrate on changes, without altering regulatory or compliance requirements.
Renewal as compliance check: Even if operations are unchanged, renewals prompt reassessment of assumptions, monitoring, and applicability, potentially affecting more than just the renewal itself.
Risks and consequences: Identified gaps during renewal can lead to notices of violation, permit modifications, increased monitoring, enforcement actions, and future scrutiny, often uncovering longstanding issues rather than new violations.
Common issues and affected industries: Problems frequently arise from outdated potential to emit assumptions, monitoring methods, operational changes, or unvalidated permit bases, impacting sectors such as manufacturing, printing, power generation, food production, petroleum, and data centers.
Leslie’s rare combination of technical expertise, client relationship skills, and community involvement is remarkable for a Young Professional, even by today’s standards. Late last week, Leslie gratefully accepted a 40 Under 40 award from the American Academy of Environmental Engineers and Scientists (AAEES). We hope you enjoy learning a little more about our colleague at SCS Engineers.
As a Project Manager at SCS Engineers, Leslie leads remediation and redevelopment of complex contaminated sites in South Florida and was an early contributor to PFAS investigation procedures. Her early career projects included national Superfund site research and large-scale investigations of military sites. She also demonstrates her commitment to community and professional development through mentoring and volunteering.
Leslie Smith exemplifies the qualities celebrated by the AAEES 40 Under 40 program and SCS values. She has multiple publications under her belt and holds a B.S. in Civil and Environmental Engineering and an M.S. in Civil Engineering (Environmental Engineering) from Florida State University, as well as a Ph.D. in Civil Engineering (Environmental Engineering) from Louisiana State University.
Technical and Business Accomplishments
Leslie has built strong, enduring relationships with major residential and commercial land developers in South Florida, earning trust through straightforward communication and effective project management of large-scale remediation projects, balancing schedules and budgets.
She manages complex environmental assessments and remediation for large-scale redevelopment projects, including a 100+ acre former golf course and agricultural properties, successfully engineering on-site reuse of contaminated soil to reduce costs and environmental impact, thereby converting contaminated sites into residential communities.
Her doctoral research involved pioneering bioremediation at scale by correlating pilot systems with full-scale Superfund site operations, characterizing microbial communities via DNA sequencing, and validating remediation efficacy—work that resulted in peer-reviewed publications and presentations.
Early in her career, Leslie was part of a large-scale site investigation at a former Cold War missile launch complex in Wyoming, addressing severe TCE contamination across a plume spanning 20,000 acres. This project shaped Leslie’s approach to contamination management.
Leslie continues to contribute her expertise to the evolving field of PFAS contamination by assisting Florida’s Department of Environmental Protection in developing Standard Operating Procedures, conducting field assessments at fire training facilities, influencing state regulatory responses, and publishing in industry publications.
Community & Civic Involvement
Water Matters Day
Leslie regularly volunteers at Deck the Halls, a community event that supports children in foster care by decorating homes for the holidays.
She also participates in Water Matters Day in Broward County, promoting water conservation through educational booths, giveaways, and activities, and in Baynanza, Miami-Dade’s celebration and cleanup of Biscayne Bay, contributing to ecological restoration efforts.
She mentors K–12 and undergraduate students in STEM education, fostering curiosity and supporting growth through lectures and research guidance. She supports affordable housing initiatives through volunteering with the Appalachian Service Project, Habitat for Humanity, and Bike & Build, aiding families with home repairs and raising awareness of housing issues.
We are extraordinarily proud of Leslie for her professional achievements and community activism, as well as our other Young Professionals at SCS, who are using their education, certifications, and expertise to demonstrate that business and protecting our environment go hand in hand.
Today’s blog discusses the challenges and opportunities related to the redevelopment of land with idle or abandoned oil wells, also known as orphan wells. At least twenty-eight states currently face the same challenge and are spending federal funds on abandoned well remediation. The majority of the orphan wells are in the Gulf Coast area, including Texas, New Mexico, Oklahoma, and Louisiana. Also, the Northern Appalachia area, including Pennsylvania, Ohio, West Virginia, New York, and Kentucky, has thousands of wells. For this blog, we focus on California, a state with unique regulatory and land-use considerations.
Due Diligence First
We stress that proximity to sensitive sites isn’t the same as risk, and we support informed, technical assessments and regulatory oversight to enable safe redevelopment, especially in urban areas. When first drilled, many wells in California were likely not in urban areas, but over time, the growth of our cities and towns has shown that they can literally now be in property owners’ backyards as well as underneath residential and commercial buildings. Conducting thorough technical evaluations is essential for safe redevelopment practices.
Understanding Risks and Redevelopment Potential
Let’s address the common misconception that proximity to orphan oil wells near schools, parks, and homes inherently means danger. We understand your concerns and will address public health and environmental risks to ensure redevelopment proceeds safely. Redeveloping former oil-field lands, often vacant lots in urban areas, can boost property values and economic growth while protecting our health through proper well-impact mitigation and access to funding sources.
Addressing Orphan Oil Wells in California (Onshore)
California faces a unique challenge: thousands of legacy oil wells are scattered across urban and rural areas. The key issue is not just their location but how these wells are evaluated, managed, and regulated amid changing land uses. The majority of oil wells are located in the Southern California counties of Kern, Los Angeles, Orange, Santa Barbara, and Ventura due to geological factors. The counties of San Bernardino, San Diego, and Riverside have the fewest number of oil wells.
California Senate Bill 1137 (2022) established health protection zones around sensitive land uses near idle or abandoned wells, reflecting California’s urban growth since many wells were drilled. Proper risk mitigation requires technical clarity on well drilling and conditions, beyond simple location maps.
Regulatory oversight is conducted by the California Geologic Energy Management Division (CalGEM), which enforces stringent standards (California Public Resources Code [PRC] § 3208.1) for well access, integrity, and abandonment. CalGEM can mandate “re-abandonment” to modern standards that emphasize cement isolation, groundwater protection, and long-term monitoring to ensure redevelopment safety. Recognizing these specific regulations helps stakeholders understand the regulatory environment guiding land reuse projects.
Integrating Development and Health Safely
There are successful redevelopment projects in areas with high numbers of abandoned wells, such as Pacific City in Huntington Beach and the 2nd & PCH shopping center in Long Beach. These projects rely on qualified petroleum engineers and geologists who conduct thorough due diligence, including review of historical well records, field verification, vapor and methane assessments, and coordination with regulators.
Where necessary, Vapor Intrusion Mitigation Systems (VIMS) are integrated into project designs to prevent toxic vapors from contaminated soil or groundwater from entering buildings, protecting indoor air quality. Early identification and mitigation during due diligence help protect public health and control costs.
Differentiating Well Types and Funding Mechanisms
Not all idle or orphan wells are the same. You can use CalGEM’s Well Finder to distinguish between well types and operators. Many wells remain under active operators with Idle Well Management Plans and bonding requirements. Truly orphaned wells mean that no responsible operator remains, but California can proceed with state plugging and sealing. These are addressed through a state-run orphan well program with four funding sources:
Ensuring Effective Regulatory Enforcement and Collaboration
The Center for Biological Diversity’s 2026 report highlighted sensitive land-use areas near wells, raising public awareness. However, effective risk reduction depends on collaboration among regulators, landowners, developers, environmental advocates, and local governments, fostering trust and shared responsibility.
CalGEM recommends engaging qualified petroleum professionals who are familiar with California’s regulatory framework for the safe, responsible evaluation of legacy wells. Early, transparent evaluations integrated into land-use planning protect communities and enable urban infill and redevelopment without undue fear or delay.
Finding the Appropriate Support to Minimize Risk
We recommend finding an engineering firm, preferably with a background in the petroleum industry and a successful track record in remediating brownfields and performing highly structured due diligence. The engineer will likely rely on the expertise of a geologist or hydrogeologist, depending on the location. You’ll want more than a due diligence consultant; you’ll need, in states like California, a California-licensed professional petroleum engineer (PE) and a California-licensed professional geologist (PG) as well. Assessing risks is complex. Firms like SCS Engineers provide the expertise to evaluate the land, complete the plug-and-abandonment process for the wells, and make properties valuable, sustainable, and useful again.
Author: Senior Project Manager and Geoscientist Tim Rathmann. Confer with Tim or an expert in your area at SCS Engineers, or reach Tim on LinkedIn.
This educational webinar explores how critical pressure informs the definition and refinement of a carbon sequestration project’s Area of Review (AoR) under the Class VI permitting framework. The SCS experts explain why some developers are re-evaluating AoR assumptions, how injection-driven pressure propagation can dominate AoR extent, and why project-specific geology (including fluid salinity and basin structure) can make simplified approaches overly conservative, rather than safer.
In this 17-minute session, we compare calculation approaches (Methods 2, 2A, and 3) and emphasize that early, iterative AoR work can reduce regulatory, cost, and public-trust risks.
AoR must account for both plume extent and pressure effects: Beyond the supercritical CO2 plume, pressurization and project critical pressure determine where fluids could migrate upward through improperly plugged/abandoned wells and potentially endanger underground sources of drinking water (USDWs).
Pressure front propagation is often the controlling factor: Pressure can propagate faster and farther than the mobile plume, and may be altered by geologic structures (e.g., faults).
Fluid salinity and density matter: Higher salinity increases fluid density and generally requires more induced pressure to drive vertical migration; real-world salinity profiles can be non-linear and project-specific.
Method selection depends on data and realism: Method 2 is simple but can yield unrealistic outcomes (e.g., zero/negative critical pressure). Method 2A uses a more detailed equation-of-state approach. Method 3 incorporates risk-based computational modeling of flow through a hypothetical, poorly-plugged well and can better handle complex cases.
Timing and iteration reduce downstream costs: Investing early and periodically re-evaluating AOR assumptions improves defensibility and can avoid costly changes after permitting.
Transparency supports outreach: The AoR process and re-evaluations (including public comment opportunities) can be communicated in plain language to build public confidence in drinking water protection.
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These funds are specifically for California to support safe plugging and abandonment of orphan wells. (Source: 
This educational webinar explores how critical pressure informs the definition and refinement of a carbon sequestration project’s Area of Review (AoR) under the Class VI permitting framework. The SCS experts explain why some developers are re-evaluating AoR assumptions, how injection-driven pressure propagation can dominate AoR extent, and why project-specific geology (including fluid salinity and basin structure) can make simplified approaches overly conservative, rather than safer.
